# year value 1900 2.359802 1901 2.323106 1902 2.333627 1903 2.051718 1904 2.081937 1905 2.186648 1906 2.237114 1907 2.277616 1908 2.303034 1909 2.299356 1910 2.350429 1911 2.319638 1912 2.408193 1913 2.27157 1914 2.324171 1915 2.394357 1916 2.436321 1917 2.420341 1918 2.393179 1919 2.405998 1920 2.472336 1921 2.477792 1922 2.497231 1923 2.494224 1924 2.487138 1925 2.497545 1926 2.48739 1927 2.520648 1928 2.527485 1929 2.490494 1930 2.448406 1931 2.4683 1932 2.489854 1933 2.447639 1934 2.411552 1935 2.526383 1936 2.602369 1937 2.536874 1938 2.563495 1939 2.585263 1940 2.512351 1941 2.54358 1942 2.574424 1943 2.617867 1944 2.635149 1945 2.538816 1946 2.554357 1947 2.554302 1948 2.614406 1949 2.621507 1950 2.58767 1951 2.609776 1952 2.593332 1953 2.55407 1954 2.566089 1955 2.593235 1956 2.619889 1957 2.591907 1958 2.608402 1959 2.636123 1960 2.634982 1961 2.588874 1962 2.568586 1963 2.451924 1964 2.32247 1965 2.373414 1966 2.414807 1967 2.450381 1968 2.448364 1969 2.44356 1970 2.494813 1971 2.603044 1972 2.659706 1973 2.647646 1974 2.604535 1975 2.606268 1976 2.639214 1977 2.627156 1978 2.700237 1979 2.720825 1980 2.808074 1981 2.812765 1982 2.650465 1983 2.581061 1984 2.691987 1985 2.700844 1986 2.757785 1987 2.840751 1988 2.899625 1989 2.929402 1990 2.985345 1991 2.904018 1992 2.598229 1993 2.774306 1994 2.763573 1995 2.866956 1996 2.98875 1997 3.0918 1998 3.080535 1999 3.14319 2000 3.117753 2001 3.217729 2002 3.282792 2003 3.207276 2004 3.269151 2005 3.32329